The technology relates to a vehicle exterior environment recognition apparatus that identifies a lighted stop lamp of a preceding vehicle.
A technique has been proposed in which a three-dimensional object, such as a preceding vehicle located ahead of an own vehicle, is detected to perform a control that avoids collision with the preceding vehicle (i.e., a collision avoidance control) or to perform a control that keeps an inter-vehicular distance between the own vehicle and the preceding vehicle to a predetermined distance (i.e., a cruise control). For example, reference is made to Japanese Patent No. 3349060. A smoother cruise control is enabled by incorporating processes such as recognizing, for example, a presence of lighting of a lamp of the preceding vehicle and presuming a decelerating operation of the preceding vehicle. The presence of lighting may be, in other words, a state of an operation of a brake. The lamp may be, for example not limited to, a stop lamp.
As a technique that detects the presence of lighting of the stop lamp of the preceding vehicle, Japanese Unexamined Patent Application Publication (JP-A) No. 2013-109391 discloses a technique in which a threshold is changed in response to brightness of a vehicle exterior environment to determine the presence of lighting of the stop lamp. The threshold relates to a size of a light-emission source identified from an image captured by an image-capturing unit.